Cylinder and method of making the same



July 27, 1943.

J. TJAARDA 2,325,288

CYLINDER AND METHOD OF MAKING SAME Filed Nov. 9, 1940 2 Sheets-Sheet 1 O 5? I\ A Q g R 2'2 J 0 O a; P

0 2 VENTOR 4 QJL Cub/n ATTOR 5Y3 July 27, 1943.

J. TJAARDA I 2,325,288

CYLINDER AND METHOD OF MAKING SAME Filed Nov. 9, 1940 2 Sheets-Sheet 2 INVENTOR fig) 7344114 4.

tions permit head temperatures of 270 C.

Patented July 27, 1943 CYLINDER AND METHOD OF MAKING SAME John Tjaarda, Detroit, Mich., assignor to Briggs Manufacturing Company, a corporation of THE ' Michigan Application November 9, 1940, Serial No. 364,962 '1 Claims. -(oi. 123-193) This invention relates particularly-but not exclusively to air cooled cylinders for internal combustion engines and to an improved method of making such cylinders.

In the development of air cooled cylinders, in an efiort to obtain lightness and maximum of power combined with good heat dissipation, it has been customary to construct a cylinder employing a cast steel barrel supporting on its outer surfaces a plurality of circumferential cooling fins or ribs and a light alloy head attached thereto. Generally. in this case the separate parts are screwed and shrunk together. In some instances, however, when barrel sizes are small they are made of cast iron. and are secured to the alloy head by means of bolts. It iswell known that in a practical use of the above cylinders at high temperatures the alloy head has a tures thereby simplifying the problem of valve lubrication.

It is a further object of the invention to provide an improved engine cylinder comprising a single unit steel barrel and head bonded integrally to a cooling jacket whereby not only a more effective transfer of heat is attained, but a cylinder is provided that is relatively light in weight, a feature which is important in the construction of modern aircraft where the reduction of Weight is an important problem.

A still further object of the invention is to provide a method of constructing an engine cylinder wherein the several parts of the above device are fused solidly by means of a furnace process, thereby providing a compositely formed cylinder whose inner sides are formed of wear resisting tendency to expand thereby causing a subsequent loosening of the head valves. The temperature of the cylinder head, generally, should not exceed 240 C. although certain known construc- It, is evident, therefore, that one of the greatest difficulties in cylinder construction is the problem of rapidly conducting heat from the heat generating areas of the cylinder to the cooling elements. Since it has been the custom to construct cylinder barrels and cooling fins of steel or iron it.naturally follows that the ability of heat transfer is necessarily limited.

It is an important object of this invention to provide an engine cylinder comprising an integrally formed cylinder'and head portion which is so constructed as to induce a relatively high rate of heat transfer from the heat generating areas within thecylinder to the cooling elements such as cooling ribs or fins.

It is another object of the invention to provide an engine cylinder comprising a single unit steel barrel and head and a cooling jacket bonded integrally thereto and composed of a metal, such as aluminum alloy, capable of rapidly dissipating heat generated in the cylinder.

. It is a further object of the invention to provide an improved cylinder of the above type wherein the possibility of head expansion and subsequent valve loosening is reduced to a minimum by means of a more rapidtransfer of heat from the cylinder head to the cooling elements.

Another object of the invention is to provide an improved engine cylinder of the above construction wherein a relatively high rate of heat transfer cools the head valve to lower temperasteel and whose outer. sides 'are comprised of a light weight relatively high heat conducting metal or metal alloy, such thereof. 1

A still further object is to provide a cylinder of the foregoing character which is simplified and economical in construction, durable, light,

compact and efilcient in use.

Other objects of this invention will appear in the flollowing description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

' Insaid drawings:

Fig. 1 is a sectional view of an aircraft engine equipped with a cylinder embodying the present invention.

Fig. 2 is-a sectional view along the lines ,22 of- Fig. 1 looking in the direction of the arrows.

Fig. 3 is an enlarged sectional view of the cylinder shown in Fig. 1.

Fig. 4' is an exploded sectional view of the cylinder shown in Fig. 1.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement. of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

Referring particularly to'Fig. 1, there is shown as aluminum or an alloy taken substantially 86a are formed in the cylinder head for the purpose of illustrating this invention a section of an aircraft engine provided with oppositely inclined banks of cylinders disposed generally in upwardly and downwardly extending positions. These cylinders 44 and 45 ar provided with pistons 48 operably connected to a crankshaft 32 through the medium of connecting rods 49 and 50 respectively. The adjacently arranged connecting rods 48 and 50 are provided with bearings 56 which are adapted to surround offset cranks of the crankshaft 32 and are se-. curely fixed thereto by means of caps 58 having threaded extensions 60 adapted to project through spaced apertures in the flared ends of the connecting rods to receiv nuts 82 to maintain the parts in assembled relationship. Each cylinder 44 and 45 may be supplied with a combustible mixture through the useof suitable fuel injectors of any known type. Air may be supplied to the cylinders through the medium of manifold passages 10 formed in the central housing 42, these passageways communicating by means of risers 18 with the upper and lower' banks of cylinders. It will be noted that the supply of combustible mixture is from the inner side of each cylinder outwardly toward the cylinder and that th exhaust gases are permitted to escape to the exhaust port 88 as shown in Fig. 2 located at the outer side of the cylinder.

In the present instance the intake of the combustible mixture into each cylinder, also the scavenging and exhaust of the products of combustion, are controlled by a valve mechanism positioned in the outer extremity of the cylinder. The intake passage for each cylinder and the exhaust passage 88 communicate with inlet and outlet ports in a rotary cone type valve 81 mounted in the cylinder head. The valve as shown in Figs. 1 and 2 has an outwardly projecting stub shaft 88 journalled through the medium of a plurality of bearing races 93 which are preloaded by means of tightening the bearing nut 94. The shaft 88 carries a bevel gear 89 in meshwith a gear 8| secured to a valve driving shaft 90. The valve actuating shaft 80 together with gearing 88 and Si operates within a longitudinally extending housing 82. The shafts 90 are preferably hollow to minimize weight and to permit the fiow of oil therethrough for lubricating purposes. Conduit 85 taps the flow of oil within the housing 82 and supplies lubrication to the bearing races 83, the rotary cone type valve 81 and the valve stub 88 The inner face of the rotary valve 81 is concaveto cooperate with the complementary convex head 48a of the piston, the valve having an interior dome-like combustion chamber 81a with which, the intake and exhaust passages 18 and 88 communicate at intervals during the rotation of the valve. The spark plug 88 communicates with the combustion chamber or cavity at predetermined intervals during the: rotation of the valve 0 for the purpose of firing the compressed mixture.

Referring particularly td Fig. 3, there is shown by way of illustration a compositely formed cylso located to cooperate with exhaust and intake passages 18 and 86. The cylinder barrel 20 is adapted to be wedged into a cooling jacket l3 which consists of a casting of aluminum or its equivalent whose outer surfaces integrally support a series of radial cooling fins or ribs |3a and whose inner surfaces I30 and 13b are shaped and dimensioned to receive the outer surfaces l0a and Ila of the cylinder barrel 20. The said jacket I3 is further provided in its upper portion with a recess or socket l8. Said socket is adapted to receive a collar or bearing nut l4 which is undercut to provide an annular fiat. shoulder portion l1 adapted to seat on a fiat ledge I8 of the cooling jacket I3. The bearing nut is also provided with areduced portion or extension I5 whose outer walls are adapted to fit snugly within an annular wall IQ of the said cooling jacket and'whose inner wails contain a female thread l5a which is adapted to receive 14 is then inserted in the socket l8 of the jacket and screwed down tightly through cooperation of the threads 12a and 15a. By drawing the bearing nut down" tightly over the end l2 of the cylinder barrel the'shoulder 11 will engage the ledge l8 of the jacket and exert pressure forcing the mating tapered portions of the jacket and cylinder head tightly together by a wedging ac- 1 tion.

Thus the separate parts of the cylinder as shown in Fig. 4 are brought into intimate contact and securely held under tension. It is to be noted that before the cylinder barrel 20 is wedged into the cooling jacket I3, the outer surface of the cylinder barrel is first ground and polished to a high finished surface. When the several parts? are thus assembled as shown in Fig, 3 they may be fused together into a substantially com posite cylinder unit by the use of any one of several suitable furnace processesnow commercially known. A satisfactory method which sist of providing a coating of fusing paste such as "Colaweld paste believed to contain iron and aluminum and which is manufactured by the inder' such as the cylinder designated as'4 4 in Fig. 1.

This cylinder comprises a barrel 20 which may be machined from a steel forging, said barrel having a cylindrical portion l0 adapted to receive the piston 48, and an integrally formed converging head portion ll terminating in an annular extension I! which is provided with a male thread I2a. Intake and exhaust ports 18a and II and are Colonial Alloys Company of Philadelphia, over the entire outer surface of the barrel with the exception of the threadedfportion 12a before assembling the parts together as described. A

' similar coating may also be applied to the outer surface of the nut 14 in order to effect a fusing of the jacket to the surfaces of the nut with which the jacket contacts. When the several parts are thus assembled as shown in Fig. 3 they.

are placed in a furnace and subjected to a'temperature in excess of about 500 F.,' such as approximately 600 F., for a sufilcient period of time during which a chemical action is believed to .occur' causing the aluminum casting to fuse solidly to the steel, thus providing substantially an integral composite cylinder unit. It is to be noted further that another method by which the composite cylinder unit may be produced is by means of casting the outer jacket together with the cooling elements to the integrally formed cylinder barrel and head. To construct the. cy-

linder in this manner any suitable casting process may be employed. While I have described one method by which the above cylinder may be produced, it will be understood that various changes maybe'made within the scope of the present invention. I claim; -1. An engine cylinder comprising a cylinder barrel having a tapered head, a cooling jacket fitting over said barrel and having a tapered portion. engageable with said tapered head, and means for securing said barrel and jacket together in tight intimate surface contact.

2. An engine cylinder comprising a cylinder barrel, a cooling jacket fitting over said barrel, and means for drawing said barrel and jacket said parts into a single composite cylinder unit,

5. The method of fabricating a composite-cylinder composed of an integrally formed barrel into tight surface contact by wedging action, said means including cooperating tapered portion on the barrel and jacket.

3. An engine cylinder comprising a cylinder barrel, a cooling jacket fitting over said barrel, means for drawing said barrel and jacket into tight surface contact by wedging action, said and head and a cast metal cooling jacket, comprising the steps of grinding and polishing the outer surface of the barrel assembling the said cooling jacket and cylinder in telescopic relation,

securing the parts together by screw threaded means to maintain said barrel under tension and said jacket under compression, and thereafter subjecting the assembled parts to heat treatment telescopic relation, securing the parts together to,

maintain said barrel under tension and said jacket under compression and thereafter subject-a meansincluding cooperating tapered portions on the barrel and jacket, and screw threaded means for drawing said portions tightly together.

4. The method of fabricating a composite .cylinder composed of an integrally formed barrel and head and a cast metal cooling jacket, comprising the steps of grinding and polishing the outer surface of the barrel, assembling the saidv separate cooling jacket fitting over said barrel, said jacket having a tapered portion engageable with said tapered extension and means for securing said barrel and jacket together in tight intimate surface, contact.

- I a JOHN'I'JAARDA. 

